How to plot another timeseries without affecting current timeseries in JFreeChart

Question

So I have a line chart with 3 different time series:

The "Voltage" line is to represent real-time data and the whole "High" and "Low" series are actually dynamically loaded from a file (whenever users click LOAD button).

The problem here is that if I load the whole "High" and "Low" series from a CSV file and then plot it while the real-time data is coming, it will show only some final points of the "High" and "Low" series and then we have to wait for the real-time data in that time period comes (which is fairly understandable).

And then my idea to fix that problem is to plot the "High" and "Low" just from the time period of the first point of the "Voltage" series to the maximum time period of the current dateaxis when I add a new point to the "Voltage" series.

public void add(Data data) throws ParseException, CloneNotSupportedException {
    Date date = new SimpleDateFormat(PATTERN).parse(data.getDate());
    Millisecond milis = new Millisecond(date);
    timeSeries.add(milis, data.getNumber());
    Date maxDate = axis.getMaximumDate();
    Date minDate = dataset.getSeries(0).getTimePeriod(0).getStart();
    Millisecond maxMili = new Millisecond(maxDate);
    Millisecond minMili = new Millisecond(minDate);
    // highSeries and lowSeries are loaded from csv file
    TimeSeries tempHighSeries = highSeries.createCopy(minMili, maxMili);
    TimeSeries tempLowSeries = lowSeries.createCopy(minMili, maxMili);
    TimeSeriesCollection collection = new TimeSeriesCollection();
    collection.addSeries(tempHighSeries);
    collection.addSeries(tempLowSeries);
    plot.setDataset(1, collection);
}

The result is the above picture. However, what I actually want is something like this:

I want the users can still see the next part of these edges (when the next points of "High" and "Low" series are not in the range of real-time data)

Any pointers?

Why not merge the High/Low data with the real-time Voltage data as the latter arrives? — trashgod, Apr 09 '17 at 19:53
Could you please give me more details with some lines of code as an example? — Forrest, Apr 09 '17 at 23:41
Yes, add the data in your implementation of `process()`, for [example](http://stackoverflow.com/a/13205322/230513). — trashgod, Apr 10 '17 at 00:26
So you mean: use SwingWorker to read that csv file and update high and low series in the process() method? My intention is to load the High and Low series without affecting the Voltage series — Forrest, Apr 10 '17 at 03:18

score 1 · Accepted Answer · edited May 23 '17 at 10:30

You'll need to address several issues to get the desired result. Assuming three TimeSeries having keys "High", "Low" and "Voltage",

Collect data in the background using SwignWorker, as shown here.
In your implementation of process(), add newly arrived values to "Voltage" and merge existing values of "High" and "Low" at the relevant times.
Let t_n be such a time. At t_n+1, it's too soon to add the next value of, for example, "High". Instead, determine the value of a new point that lies on the projection of "High" using linear interpolation, as shown here. Each such line will be bounded by successive values of "High", shown in thick, hand-drawn blue in your diagram. The new point may be added temporarily, updated between successive values, and finally replaced when it's time for a new value of "High".
Do likewise for "Low".
You can omit the shape for the temporary points by overriding getItemShape(), as shown here, and returning an empty shape as needed.

How to plot another timeseries without affecting current timeseries in JFreeChart

1 Answers1